As known in the art, in a hybrid vehicle including two drive sources, an internal combustion engine and a motor, automatic stopping and automatic restarting of an engine operation are repeated when the vehicle is stopped or travelling. The automatic stopping and automatic restarting of the engine operation are repeatedly performed even in an internal combustion engine that performs a so-called economy running control that automatically stops the engine operation when stopping the vehicle such as when stopping at a traffic light or the like. In a vehicle that intermittently operates the vehicle internal combustion engine, it is desired that the engine vibration when restarting the engine be suppressed to an extent that the driver does not notice the restarting of the engine operation.
A variable valve actuation mechanism is applied to a vehicle internal combustion engine as a mechanism that varies the valve properties of engine valves (intake/exhaust valves). A variable valve timing mechanism for varying the valve timing of the engine valve, a variable actuation angle mechanism for varying the actuation angle of the engine valve, and the like are known variable valve actuation mechanisms.
Conventionally, a device described in patent document 1 is proposed as a controller for a vehicle internal combustion engine that includes a variable actuation angle mechanism and is mounted on a hybrid vehicle. In the vehicle internal combustion engine to which the controller described in the document is applied, to ensure the startability of the engine, the engine operation is restarted when the actuation angle of the engine valve is greater than the minimum actuation angle in the variable range. Thus, when the variable actuation angle mechanism becomes defective when the actuation angle of the engine valve is at the minimum actuation angle, a starting failure of the vehicle internal combustion engine may occur. Accordingly, the controller of the document prohibits automatic stopping of the engine operation so that a situation in which restarting cannot be performed is avoided if the variable actuation angle mechanism becomes defective when the actuation angle of the engine valve is at the minimum actuation angle.